24 G. LINDSTRÖM, THE ASCOCERATIDZE AND THE LITUITIDAZ. 
The shell is nearly perfectly cylindrical with quite circular section, a little enlarged 
at half the height and narrower towards both ends. A necklike constriction exists just 
above the top of the sigmoid septa. The margins of the circular aperture which seems 
to be entire, are very thin and uneven. 
The surface is transversally annulated by faintly projecting ridges. These are co- 
vered with parallel, sharp and threadfine transverse lines, somewhat imbricating and in 
their turn again crossed by most delicate longitudinal lines, both forming a network, 
especially near the aperture. For the rest the shell is smooth and glossy between the 
transverse lines. In some specimens again the longitudinal lines continue all way down, 
making the whole surface reticulate. 
'The transverse lines are rather unequally crowded, more numerous on the ridges 
and absent or scanty between them. "There are about 26 on a length of 6 mm:s, while 
the annular ridges on the same distance are only 6. The transverse lines and the ridges 
are curved downwards on the ventral side. 
There are four sigmoid septa and below them only the septum of the truncature, 
the intermediate septum, present in the preceding species, being absent in all specimens 
of Asc. pupa. The greatest breadth of the sigmoid septa amounts to 7 millim:s, breadth 
at the saddle 4 millim:s. 
The septum of the truncature is thick and in direct continuation with the thick 
lining which covers the inside of the shells. 
A narrow oblique duct combines the siphuncle of the Nautiloid with that of the 
Ascoceras. This duct, which is widening upwards, where it opens in the Ascoceras si- 
phuncle, is closed below by thick deposits around its inferior aperture. The Ascoceras 
siphuncle is situated close agaimst the ventral side of the shell, whilst that of the Nauti- 
loid is placed at a little distance from that side. In no other species the siphunele has this 
position. There are four elements, the first large and beadlike. The three superior elements 
are very short and transverse. On the inferior surface of the septum (fig. 51) of the 
truncature the siphuncle of the Nautiloid stage is seen encireled with a strong neck. The 
smaller ring is derived from the interior deposits. 
Length 24 millim., largest diam. 9 millim. 
5. Ascoceras reticulatum n. 
Pl. I fig. 53-56. 
Found only in one specimen in the uppermost limestone of Sandarfve kulle. 
General shape cylindrical, laterally compressed, and the section is consequently oval, 
ventral and dorsal sides convex, the ventral more so. The aperture is broken off, but by its 
basis it may be seen that it has been broad and bent towards the dorsal side. "The sur- 
face of the shell is even, without any annular elevations, densely sculptured by sharp trans- 
verse lines, as many as seven on a length of one mill. and curved downwards on the 
ventral side. Seen in profile each line forms a projecting angle or tooth, the superior 
side of which is a little longer than the inferior one. Faint longitudinal lines cross them, 
forming small points where they meet, and are larger in the interspaces. The inferior trunca- 
ted end is fragmentary. There are four sigmoid septa nearly resembling those of Ascoc. pupa. 
BESS FSA RS Sa 
de 
